JP2014138505A - Shaft grounding device of rotary machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shaft grounding device of a rotary machine which securely grounds a rotation shaft achieving low resistance, prevents the occurence of dust caused by friction, eliminates spare items for an expendable item, and does not need the stoppage of the rotary machine which results from replacement of the expendable item.SOLUTION: A shaft grounding device of a rotary machine comprises: a grounding plate 12 which is integrally attached to a rotation shaft 14 of a rotary machine so as to extend in a radial direction of the rotation shaft 14; and a liquid tank 13 which stores a conductive liquid 16 and is installed so that the liquid 16 and the grounding plate 12 contact with each other, the liquid 16 being grounded in the liquid tank 13.

Description

  Embodiments described herein relate generally to a shaft grounding device for a rotating machine that grounds charges accumulated on a rotating shaft.

  In general, some rotating machines such as electric motors and generators require shaft grounding. For example, since an inverter-driven electric motor includes harmonics in its driving power supply, electric charges are likely to accumulate based on the capacitance between the electric motor and the stator. It is known that electric charges accumulate on the rotor shafts of other generators and steam turbines. As described above, when electric charges are accumulated on the rotating shaft of the rotating machine, the electric corrosion of the bearing is caused. Therefore, it is necessary to ground the rotating shaft to release the electric charges.

  As a shaft grounding method for this purpose, there is known a method in which a shaft serving as a rotating body and a carbon brush serving as a non-rotating body are brought into contact with each other and grounded via the carbon brush to release the shaft charge. However, the shaft contact method using the carbon brush is sufficiently affected by the operating environment because there is a resistance value on the contact surface between the brush and the slip ring because the carbon brush is in contact with the rotating body (slip ring). There is no reliability. Also, replacement is necessary according to the wear of the brush, and it is necessary to have spare parts, and dust due to carbon wear has been a problem. Furthermore, it was necessary to stop the rotating machine in order to replace the carbon brush.

  For this reason, the structure which makes the brush exchange for grounding easy is proposed (for example, refer patent document 1). However, even in this proposal, there is no substitute for grounding by contact with the rotating body, and the above-described problems associated with contact (friction) with the rotating body are present.

JP 2003-254007 A

  As described above, in the conventional shaft grounding method, the shaft, which is a rotating body, is brought into contact with the carbon brush, and the carbon brush is grounded to remove the shaft charge. For this reason, it is necessary to replace the carbon brush in accordance with the consumption of the carbon brush, and there is a need to have a spare part and a problem of dust due to carbon wear.

  Therefore, the present invention can reliably ground the rotating shaft with low resistance, eliminate the generation of dust caused by friction and the spare parts of consumables accompanying friction, and also requires the rotating machine to be stopped due to replacement work. An object of the present invention is to provide a shaft grounding device for a rotating machine that does not.

  A shaft grounding device for a rotating machine according to an embodiment of the present invention includes a grounding plate integrally attached to a rotating shaft of the rotating machine so as to extend in the radial direction, and a conductive liquid accommodated therein. And a liquid tank installed so that the liquid and the ground plate are in contact with each other, and a terminal connected to a conductor led out from the liquid to the outside.

  According to the present invention, since the shaft is grounded via the liquid, the rotating shaft is grounded with an extremely low resistance value. In addition, there are no consumables, running costs are reduced, and dust due to wear during contact is not generated. Furthermore, the liquid can be changed while the rotating machine is in operation, and it is not necessary to stop the rotating machine for maintenance.

It is sectional drawing of the shaft grounding apparatus of the rotary machine which concerns on 1st embodiment of this invention. It is sectional drawing of the shaft grounding apparatus of the rotary machine which concerns on 2nd embodiment of this invention. It is sectional drawing of the shaft grounding apparatus of the rotary machine which concerns on 3rd embodiment of this invention. It is sectional drawing of the shaft grounding apparatus of the rotary machine which concerns on 4th embodiment of this invention. It is sectional drawing of the shaft grounding apparatus of the rotary machine which concerns on 5th embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  In the embodiment of the present invention, when the rotating shaft of a rotating machine such as an electric motor or a generator is grounded, the grounding plate provided on the rotating shaft is immersed in a liquid, and a simple grounding that releases electric charges through the liquid. The configuration is adopted.

  In the first embodiment shown in FIG. 1, the shaft grounding device 11 includes a grounding plate 12 and a liquid tank 13. The grounding plate 12 has a disc shape and has a rotating shaft 12a that is integrally connected to a rotating shaft 14 of a rotating machine body (not shown). And it is integrally formed so that it may extend in the radial direction from the outer periphery of this rotating shaft 12a. Therefore, the ground plate 12 is synonymous with a structure that is integrally attached to the rotating shaft 14 of the rotating machine so as to extend in the radial direction.

  The liquid tank 13 contains a conductive liquid 16 therein, and is configured such that at least a part of the ground plate 12 contacts the liquid 16. The liquid 16 is grounded via a conductor 18 connected to a ground terminal 17 in the liquid. In addition, an opening 21 for injecting liquid 16 is provided at the top of the liquid tank 13 and an opening 22 for discharging is provided at the bottom, which are always closed by a plug.

  Here, since at least a part of the above-described ground plate 12 is always immersed in the liquid 16, it is formed of a metal body having high rust resistance, such as stainless steel. The liquid 16 may be anything as long as it has conductivity, but can be easily obtained by using tap water.

  According to the above configuration, the electric charge accumulated on the rotating shaft 14 of the rotating machine flows to the liquid 16 through the ground plate 12 integrally connected to the rotating shaft 14 and is grounded through the ground terminal 17 and the conductor 18 in the liquid. The flow can escape from the rotating shaft 14. For this reason, it is possible to effectively prevent electric corrosion from occurring on the bearing due to the electric charge accumulated on the rotating shaft 14.

  Further, the ground plate 12 is integrally attached so that the plate surface extends in the radial direction of the rotary shaft 14, and at least a part of the ground plate 12 is immersed in the liquid 16. The mechanical resistance received from the liquid 16 is small, and power loss due to contact with the liquid 16 can be minimized.

  Further, the shaft grounding device 11 using the liquid 16 according to this embodiment is not worn by contact with the rotating shaft side like a conventional carbon brush, so that dust is generated due to wear of the carbon brush. Absent. Moreover, since there is no need to replace parts due to wear, it is possible to save time and effort for preparing replacement parts.

  Of course, since the liquid 16 also changes its water quality over a long period of time, it is necessary to replace the liquid 16 after a certain period of time. However, the replacement is only the discharge and injection of the liquid 16 from the liquid tank 13. The operation of the rotating machine can be easily performed without stopping, and the operating efficiency of the rotating machine does not decrease.

  Next, a second embodiment shown in FIG. 2 will be described. In this embodiment, a plurality of ground plates 12 are attached at intervals with respect to the axial direction of the rotating shaft 14. With this configuration, a large number of disk-shaped grounding plates (metal bodies) 12 are immersed in the liquid 16, so that the cross-sectional area of contact with the liquid 16 is increased, and the electrical conductivity is improved. Realize and improve reliability.

  Next, a third embodiment shown in FIG. 3 will be described. In this embodiment as well, a plurality of ground plates 12 (12A, 12B) are attached to the axial direction of the rotating shaft 14 at intervals, but the plurality of ground plates 12A, 12B are attached to each other. These are individually in contact with the conductive liquids 16A and 16B in the liquid tanks 13A and 13B provided for each ground plate. Then, an external power source 24 is connected between the liquids 16A and 16B in the liquid tanks 13A and 13B via connection terminals 23A and 23B, thereby enabling continuity check between the liquids 16A and 16B.

  A rotating machine main body (not shown) is located between the illustrated liquid tanks 13A and 13B, and the rotating shafts 12Aa and 12Ba of the ground plate are integrally connected to the rotating shaft 14 at both ends of the rotating machine main body, respectively. . For this reason, the liquid 16A in one liquid tank 13A from the external power source 24, one grounding plate 12A and its shaft 12Aa, the rotating shaft 14 of the rotating machine body, the other grounding plate shaft 12Ba and the grounding plate 12B, the other liquid tank A closed circuit reaching the external power source 24 through the liquid 16B in 13B is formed. Therefore, by conducting a continuity check between the liquids 16A and 16B, a continuity check is performed between the ground plates 12A and 12B and the corresponding liquids 16A and 16B. You can always check that you are grounded.

  In FIG. 3, the liquid tanks 13 </ b> A and 13 </ b> B are configured by separate containers. However, as in the fourth embodiment shown in FIG. 4, a partition 28 is provided in a common container 27 to provide individual liquids. Even if the tanks 13A and 13B are formed, other configurations are the same as those in FIG. 3, and corresponding portions are denoted by the same reference numerals.

  Even with this configuration, by conducting a continuity check between the liquids 16A and 16B, a continuity check between the ground plates 12A and 12B and the corresponding liquids 16A and 16B is performed. It can always be confirmed that the accumulated electric charge is securely grounded.

  Next, a fifth embodiment shown in FIG. 5 will be described. This embodiment relates to the exchange of the liquid 16 with respect to the liquid tank 13, and an auxiliary tank 30 is provided outside the liquid tank 13 so as to be movable up and down. The bottom opening 31 of the auxiliary tank 30 communicates with the bottom opening 22 of the liquid tank 13 via a pipe line 31. And the liquid 16 in the liquid tank 13 can be taken in and out by the pressure difference with the liquid tank 13 accompanying the vertical movement of the auxiliary tank 30.

  That is, when the liquid 16 in the liquid tank 13 is discharged, the auxiliary tank 30 is lowered from the illustrated position, so that the liquid 16 in the liquid tank 13 is discharged into the auxiliary tank 30 due to a pressure difference from the liquid tank 13. be able to. When the liquid 16 is injected into the liquid tank 13, the bottom surface of the auxiliary tank 30 is positioned at the same height as the bottom surface of the liquid tank 13 so that the liquid in the auxiliary tank 30 is equal to the liquid level. The liquid tank 13 can be injected up to the liquid level.

  With this configuration, even when the shaft grounding device 11 is installed in a place where an operator cannot approach during operation of the rotating machine, the auxiliary tank 30 is operated to operate the liquid tank 13. It becomes possible to exchange the liquid 16 in the inside without approaching. That is, maintenance can be safely performed even during operation.

  In each of the embodiments described above, the ground plate 12 is a disk-shaped metal body. However, the present invention is not limited to this, and for example, a fan-shaped metal body is attached along the outer periphery of the rotating shaft, or a plurality of strip-shaped metal bodies. May be arranged radially along the outer periphery of the rotating shaft.

  Further, although the ground plate 12 is integrally connected to the rotating shaft 14 of the rotating machine body via the integral shaft 12a, it may be directly attached to the outer periphery of the rotating shaft 14 without using the shaft 12a. .

  Although several embodiments of the present invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 11 ... Shaft grounding device 12 ... Grounding plate 13 ... Liquid tank 14 ... Rotating shaft 16 ... Liquid 17 ... Grounding terminal 18 ... Conductor 24 ... External power supply 30 ...・ Auxiliary tank 31 ・ ・ ・ Pipe

Claims (4)

A ground plate integrally attached to the rotating shaft of the rotating machine so as to extend in the radial direction;
Conductive liquid is contained inside, a liquid tank installed so that the liquid and the ground plate are in contact with each other, and a terminal connected to a conductor led out from the liquid, and
A shaft grounding device for a rotating machine.   The shaft grounding device for a rotating machine according to claim 1, wherein a plurality of the grounding plates are attached at intervals in the axial direction of the rotating shaft.   The plurality of ground plates individually contact with the conductive liquid in the liquid tank provided for each of the ground plates, and an external power source is connected between the liquids in each liquid tank. The shaft grounding device for a rotating machine according to claim 2, wherein the continuity check is possible.   It is provided outside the liquid tank so as to be movable up and down, communicates with the bottom of the liquid tank via a pipe line, and the liquid in and out of the liquid tank is brought into and out of the liquid tank due to a pressure difference between the liquid tank and the vertical movement. The shaft grounding device for a rotating machine according to any one of claims 1 to 3, further comprising an auxiliary tank that enables the rotation of the rotating tank.

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